class Solution
{
 public:
  double myPow(double x, int n)
  {
    if (x == 0) return 0;
    long b = n;
    double res = 1.0;
    if (b < 0)
    {
      x = 1 / x;
      b = -b;
    }
    while (b > 0)
    {
      if ((b & 1) == 1) res *= x;
      x *= x;
      b >>= 1;
    }
    return res;
  }
}